A strain of cockroaches in Europe has evolved to outsmart the sugar traps used to kill them, researchers have discovered.

According to the BBC, American scientists found that the mutant cockroaches had a "reorganized" sense of taste, making them perceive the glucose used to coat poisoned bait not as sweet but rather as bitter.

A North Carolina State University team tested the theory by giving cockroaches a choice of jam or peanut butter.

In the first part of the experiment, the researchers offered the roaches a choice of peanut butter or glucose-rich jelly.

"You can see the mutant cockroaches taste the jelly and jump back - they're repulsed and they swarm over the peanut butter," Dr. Coby Schal told the BBC.

The scientists then immobilized the cockroaches and used tiny electrodes to record the activity of the pest's taste receptors.

"The cells that normally respond to bitter compounds were responding to glucose in these [mutant] cockroaches," said Schal.

"So they're perceiving glucose to be a bitter compound."

The team attributed the roaches' reorganized sense of taste to natural selection, the same process that has led to the evolution of antibiotic resistance in disease-causing bacteria.

Schal said this was another chapter in the evolutionary arms race between humans and cockroaches.

"We keep throwing insecticides at them and they keep evolving mechanisms to avoid them," he said. "I have always had incredible respect for cockroaches," he added. "They depend on us, but they also take advantage of us."